Mikkel seems to have a quiet personality, which contrasts with Sigrun Eide's energetic one. He displays a no-nonsense approach to compelling Lalli into a handshake when the latter tries to walk away from one. He gets fired often, probably because he has a fondness for sarcasm and pranks.

Although he seems rather laid-back, Mikkel is very skilled and experienced. He is as knowledgeable as Sigrun about the outside world and its dangers, and knows the capabilities (or lack thereof) of his teammates better than her.

Mikkel was recruited to the mission by Trond Anderson, which suggests that perhaps they worked together in the past. However, unlike the rest of the crew, it seems that Mikkel doesn't have strong relations with any of the expedition's organizers.

Mikkel serves as the Expedition's medic and cook, so he presumably has good capabilities in both areas. His introduction also states him to be a farmer, so it is unclear how much involvement he has with the military. Much like Signe Sørensen, he is often in between jobs.

He is Sigrun Eide's second-in-command in the expedition, as they both have much more experience than the other three official crew members.

Mikkel was born and grew up on the Madsen family farm. At some point he grew bored with farming and enlisted in the Military. This led to him often having to move around from one assignment to another, which was not helped by his tendency to get fired often.

The crew started out by crossing the Öresund bridge and going through the Drogden tunnel past it. After 90 years of inadequate maintenance, the bridge was unstable and started to collapse under the weight of their vehicle.

The Crew's first mission was to journey to Kastrup, a suburban area outside of the Copenhagen city ruins. Sigrun, Emil and Lalli went inside to explore a building which used to house a library within a community space. Mikkel stood outside to guard and keep Tuuri company.

Sigrun and the others found a lot of books, and they brought some out for Mikkel to take back to the vehicle. Mikkel tells Tuuri that she is not allowed to read the books until they have been de-contaminated.

Sometime later, the crew inside realized that the building was infected by trolls. Mikkel, stationed outside, realized that it was time to go when he witnesses the explosion coming from inside the building. He yelled at Tuuri to start the vehicle, just as Sigrun and Emil came out of the building. Even during this time, Mikkel had the presence of mind to ask them where the scout was, who the others had forgotten about. Fortunately, Lalli reunited with them by crashing through an second floor window and falling into Mikkel's arms.

After the crew flee to the Cattank and drive away to safety. Mikkle appoints Tuuri to find a safe place for the crew to stay Sigrun excitedly rants that the skirmish was "The Awesomest", surprising Emil into vomitting and Lalli into covering his ears. Mikkel seperates to two, placing Sigrun in a corner to face the wall and decides its best to clean up the crew.

The next morning, the crew camp out at Kastrup Fort where Mikkel berates Sigrun about the choice of books they brought back but states that not all of them are irrelevant as the book that Lalli picked up captures his interest. The book is shown to detail the effects of the The Rash disease on a victim, likely a patient from the hospital how contracted the disease.

Mikkel, Sigrun and Tuuri continue to banter about whether the crew is ready to venture further into the city while Emil and Lalli rest in the Cattank.

Later, Mikkel is seen outside cooking breakfast for the crew. Lalli soon joins them as Emil complains that it shouldn't take so long for Mikkel to make breakfast. As Mikkel dumps the ingredients into the pot Tuuri brought, the bottom gives away and the food is sadly burnt, leading him to seek for more food from the Cattank. However, it turns out that their supply of food had been mixed up and they have been left with a surplus of cat candles. He borrows the radio from Tuuri to contact the Västerström company and notify them of their situation to ship emergency supplies for the crew. When they are told that permission for shipment of supplies to the Silent World wouldn't come in time, Trond steps in to blackmail the captain of the Túnfiskurinn into shipping a crate of supplies to them.

Mikkel is the expedition's oldest member, as confirmed by the author in a preview blog post. Nonetheless, he's still younger than Siv Västerström, the youngest of the expedition's organizers.

Mikkel and Michael Madsen, date unknown

Mikkel appears to be able to make cookies, to which Lalli has taken a great liking to.

"Mikkel" is a first name originating from Old Norse, and still quite frequent throughout the Nordics. The Namespedia currently knows of 71 "Mikkel Madsen"s.

Mikkel insists on referring to Michael as his "technically older" brother; they are twins.

Mikkel is shown to be incapable of firing a firearm accurately. According to Minna, though, this is not due to near-sightedness or similar problems, but to deficiencies of his brain's processing of his vision.